A malocclusion is a misalignment of teeth or incorrect relation between the teeth of the two dental arches. The term was coined by Edward Angle, the “father of modern orthodontics,” as a derivative of occlusion, which refers to the way opposing teeth meet. Angle based his classifications of malocclusions on the relative position of the maxillary first molar. According to Angle, the mesiobuccal cusp of the upper first molar should align with the buccal groove of the mandibular first molar. The teeth should all fit on a line of occlusion, which is a smooth curve through the central fossae and cingulum of the upper canines, and through the buccal cusp and incisal edges of the mandible. Any variations therefrom results in malocclusion.
There are three classes of malocclusions, Class I, II, and III. Further, class II is subdivided into three subtypes:
Class I: Neutrocclusion Here the molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have problems like spacing, crowding, over or under eruption, etc.
Class II: Distocclusion (retrognathism, overjet) In this situation, the upper molars are placed not in the mesiobuccal groove, but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. There are two subtypes:
Class II Division 1: The molar relationships are like that of Class II and the anterior teeth are protruded.
Class II Division 2: The molar relationships are class II but the central incisors are retroclined and the lateral incisors are seen overlapping the central incisors.
Class III: Mesiocclusion (prognathism, negative overjet) In this case the upper molars are placed not in the mesiobuccal groove, but posteriorly to it. The mesiobuccal cusp of the maxillary first molar lies posteriorly to the mesiobuccal groove of the mandibular first molar. This malocclusion is usually seen when the lower front teeth are more prominent than the upper front teeth. In such cases, the patient very often has either a large mandible or a short maxillary bone.
Orthodontics is a dental specialty that treats malocclusion through the movement of teeth as well as the control and modification of facial growth. This process is usually accomplished by using a continuous mechanical force to induce bone remodeling, thereby enabling the teeth to move to a better position. In this approach, orthodontic appliances provide a continuous static force to the teeth via an archwire connected to brackets affixed to each tooth or via a removable appliance such as an aligner, or some similar accessory, that fits over the dentition. As the teeth slowly move due to the orthodontic force, the force is dissipated. The archwires are adjusted to add additional force and to continue the desired tooth movement. Although effective, this widely accepted approach takes about twenty-four months on average to achieve success.
Researchers have long postulated that a pulsating force might also be used to move teeth more rapidly and to ease the discomfort of traditional orthodontics, but Mao was probably the first to prove that the use of cyclic forces could speed bone remodeling in rabbits (see U.S. Pat. No. 6,684,639, U.S. Pat. No. 6,832,912, U.S. Pat. No. 7,029,276). Certain dynamic loading patterns (cycling force with rest periods) were shown to greatly increase bone formation compared to basic dynamic loading. Inserting rest periods is now known to be especially efficacious as it allows mechanosensitivity to be restored to the bone tissue. A point of diminishing returns is reached within each loading session. Therefore, intermittently loading cyclic force can increase the rate of bone formation significantly.
Although promising, Mao studied rabbit cranial suture closure and facial lengthening, and his results, while suggestive, could not be presumed to apply to humans. In addition, the Mao device was completely unsuitable for clinical testing.
OrthoAccel Technologies Inc., invented the first FDA cleared and commercially successful orthodontic vibrating device, as described in US20080227046, designed to apply cyclic forces to the dentition for accelerated remodeling purposes. Both intra-oral and extra-oral embodiments are described in US20080227046, each having processors to capture and transmit patient usage information. The bite plate was specially designed to contact occlusal as well as lingual and/or facial surfaces of the dentition, and thus was more effective than any prior art devices in conveying vibrational forces to the teeth.
Further, the device was tested in clinical trials and shown to speed orthodontic remodeling as much as 50%. Thus, it is truly a breakthrough in orthodontic technology. Finally, the device is slim, capable of hands free operation, lacks the bulky head gear of the prior art devices, and has optimized force and frequency for orthodontic remodeling and only requires 20 minutes usage per night for clinical efficacy. Thus, its comfort level and compliance was also found to be high, with patients reporting that they liked the device, especially after the motor was redesigned to be quieter and smoother, as described in US2010055634 et seq.
In fact, this device has been marketed as AcceleDent® in several countries and has achieved remarkable commercial success since its introduction. AcceleDent® represents the first successful clinical approach to accelerate orthodontic tooth movement by modulating bone biology in a non-invasive and non-pharmacological manner.
One of the interesting side effects in using the AcceleDent® with thousands of patients, is that the orthodontist with the experience and savvy to capitalize on the faster bone remodeling are able to change their treatment plans accordingly. Thus, many practitioners are changing aligner trays every 5-7 days instead of the recommended 14 days, and the patient are thus able to fully realize the decreased treatment time.
However, the basic paradigm of 22-7 aligner usage has not changed. Aligners are cleared for usage the entire day and night, being removed only to eat and brush. Practitioners do not recommend night time-only use, and indeed, most actively counsel against it, noting that the treatment times may be correspondingly increased or that treatment gains can even be reversed during the period of non-use.
This disclosure turns that paradigm around and provides night time usage of aligner, but only when coupled with micropulse vibration or another accelerator modality.